In a distributed Bragg reflector (DBR) laser, a gain medium is in optical communication with one or more grating structures that define reflection peaks that control which wavelengths of light are reflected back into the gain section and amplified for output from the laser cavity. The grating structures therefore can be used to control the output spectrum of the laser. Where two grating structures are used having different free spectral ranges, the output spectrum of the laser is determined by the alignment of the reflective spectrum of the two grating structures. The alignment of the reflection spectrum may be shifted with respect to one another to accomplish a shift in the output frequency of the laser that is much larger than the frequency shift of the reflection spectrum due to the Vernier effect.
In most DBR lasers current injection is used to tune the reflection peaks of the grating structures. However, current injection tends to degrade the materials of the DBR section over time, which limits the useful life of transmitters using current injection.
In other DBR lasers the reflection spectrum is shifted by changing the temperature of the grating structures due to the thermo-optic effect. Temperature tuning does not shorten the useful life of a DBR laser to the same extent as current injection. However, prior temperature tuning systems and methods have high power requirements, slow frequency response, and narrow tuning bands.
Therefore, it can be advantageous to tune a DBR to have faster speed in a manner that does not degrade its materials or have high power requirements.